/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sf.webdav.fromcatalina;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.BitSet;

/**
 * 
 * This class is very similar to the java.net.URLEncoder class.
 * 
 * Unfortunately, with java.net.URLEncoder there is no way to specify to the
 * java.net.URLEncoder which characters should NOT be encoded.
 * 
 * This code was moved from DefaultServlet.java
 * 
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 */
public class URLEncoder {
    protected static final char[] hexadecimal = { '0', '1', '2', '3', '4', '5',
	    '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

    // Array containing the safe characters set.
    protected BitSet safeCharacters = new BitSet(256);

    public URLEncoder() {
	for (char i = 'a'; i <= 'z'; i++) {
	    addSafeCharacter(i);
	}
	for (char i = 'A'; i <= 'Z'; i++) {
	    addSafeCharacter(i);
	}
	for (char i = '0'; i <= '9'; i++) {
	    addSafeCharacter(i);
	}
    }

    public void addSafeCharacter(char c) {
	safeCharacters.set(c);
    }

    public String encode(String path) {
	int maxBytesPerChar = 10;
	int caseDiff = ('a' - 'A');
	StringBuffer rewrittenPath = new StringBuffer(path.length());
	ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
	OutputStreamWriter writer = null;
	try {
	    writer = new OutputStreamWriter(buf, "UTF8");
	} catch (Exception e) {
	    e.printStackTrace();
	    writer = new OutputStreamWriter(buf);
	}

	for (int i = 0; i < path.length(); i++) {
	    int c = (int) path.charAt(i);
	    if (safeCharacters.get(c)) {
		rewrittenPath.append((char) c);
	    } else {
		// convert to external encoding before hex conversion
		try {
		    writer.write((char) c);
		    writer.flush();
		} catch (IOException e) {
		    buf.reset();
		    continue;
		}
		byte[] ba = buf.toByteArray();
		for (int j = 0; j < ba.length; j++) {
		    // Converting each byte in the buffer
		    byte toEncode = ba[j];
		    rewrittenPath.append('%');
		    int low = (int) (toEncode & 0x0f);
		    int high = (int) ((toEncode & 0xf0) >> 4);
		    rewrittenPath.append(hexadecimal[high]);
		    rewrittenPath.append(hexadecimal[low]);
		}
		buf.reset();
	    }
	}
	return rewrittenPath.toString();
    }
}
